Myths are generally stories based on tradition and legend designed to explain the universal and local beginnings ("creation myths and "founding myths"), natural phenomena, inexplicable cultural conventions, and anything else for which no simple explanation presents itself. Not all myths need have this explicatory purpose, however. Likewise, most myths involve a supernatural force or deity, but many simple legends and narratives passed down orally from generation to generation have mythic content. The Brothers Grimm demonstrated that there is mythic content embedded even in the least promising fairy tales.

A fairy tale itself is not a myth. Other examples of materials with mythic content that are not themselves myths:

What forces generate myths? Robert Graves said of Greek myth "True myth may be defined as the reduction to narrative shorthand of ritual mime performed on public festivals, and in many cases recorded pictorially." (The Greek Myths, Introduction). Graves was deeply influenced, perhaps too strongly, by Sir James George Frazer's mythographyThe Golden Bough and he would have agreed that myth is generated by many cultural needs (more on the forces that generate myth is needed)

What human needs do myths satisfy? Myths authorize the cultural institutions of a tribe, a city, a nation by connecting them with universal truths. Myths justify the current occupation of a territory by a people, for instance.

Mythology figures prominently in most religions, and most mythology is tied to at least one religion. Some use the words "myth" and "mythology" to portray the stories of one or more religions as false, or dubious at best. The term is most often used in this sense to describe religions founded by ancient societies, such as Roman mythology, Greek mythology, and Norse mythology, which were nearly extinct at one time. However, it is important to keep in mind that while some view the Norse and Celtic pantheons as mere fable, others hold them as a religion (See Neopaganism). By extension, many people do not regard the tales surrounding the origin and development of religions like Christianity, Judaism and Islam as literal accounts of events, but instead regard them as figurative representations of their belief systems.

Some people, especially within "revealed" religions that are justified in terms of an authenticated scripture, may take offense at the characterization of any aspect of their faith as an expression of myth. An aspect of fundamentalism requires that every incidental element be accepted as literally true. However, most people concur that every religion has a body of myths that express deeper truths that are ineffable on the surface level.

For the purposes of this article, therefore, we use the word "mythology" to refer to stories that, while they may or may not be strictly factual, reveal fundamental truths and insights about human nature, often through the use of archetypes. Also, the stories we discuss express the viewpoints and beliefs of the country, time period, culture, and/or religion which gave birth to them; thus one can speak of a Jewish mythology, a Christian mythology, or an Islamic mythology, in which one describes the mythic elements within these faiths without speaking to the veracity of the faith's tenets or claims about its history.

Many modern day rabbis and priests within the more liberal Jewish and Christian movements, as well as most Neopagans, have no problem viewing their religious texts as containing myth; they see their sacred texts as indeed containing religious truths, divinely inspired but delivered in the language of mankind. Others, of course, disagree.

However, copyright law restricts independent authors from extending modern story cycles. Some critics believe that the fact that the core characters and stories of modern story cycles are not in the public domain prevents the modern story cycles from sharing several essential aspects of mythologies. Fan fiction goes some distance to relieving this problem.

Fiction, however, does not reach the level of actual mythology until people believe that it really happened. For example, some people believe that fiction author Clive Barker's Candyman was based upon a true story, and new stories have grown up around the figure. The same can be said for the Blair Witch and many other stories.